A manual switch for direct current reversible electric winch motors, which switch includes a switch housing that may be mounted on or built into the winch housing of an electric winch or connected by means of appropriate wiring to the electric winch motor for operating the winch under circumstances where automatic operation of the winch is not possible. The switch housing includes four fixed contacts that are electrically isolated from each other and from the housing and a pair of contact bars which are spring-loaded inside the housing to facilitate selective engagement with the respective fixed contacts responsive to manual operation of the switch to operate the reversible electric winch motor in the forward or reverse direction. The contact bars may be moved directly by hand manipulation of a handle-turret assembly attached to the switch housing or by a push-pull knob arrangement or more remotely, by energizing a pair of solenoids attached to the switch housing or a rotary actuator mounted on the switch housing or manipulating a remote handle connected to a remote handle bracket attached to the turret assembly of the switch housing by means of wires.

1. Field of the Invention
This invention relates to winch systems for four-wheel drive vehicles and other vehicles and more particularly, to a manual switch for operating direct current (DC) reversible electric winch motors under circumstances where the conventional winch electrical operating system fails. The manual switch is designed to be mounted in or on the winch housing or electrically coupled to the DC electric winch motor in the winch to serve as a backup system for operating the winch. The manual switch of this invention may typically be operated in four ways, including hand-manipulation of a handle-turret assembly or a push-pull knob arrangement mounted on the switch housing, remotely manipulating the handle turret assembly by means of a remote handle connected to the turret by means of wires, and remotely operating the switch by means of solenoids or a rotary actuator mounted on the switch housing and connected to a toggle or other switch by appropriate wiring.
One of the problems inherent in the operation of conventional winch systems and particularly winch systems mounted on four-wheel drive vehicles used for hunting, oil and gas operations and other activities involving operation of the vehicles in remotely located places, is that of moisture, mud, corrosion and other contamination of the various electrical contacts and connections necessary to operate conventional winch systems. Conventional winches are typically operated by four solenoid (SPST) or two solenoid (DPST) electrical arrangements. External connections found in these winch configurations are extremely prone to malfunction due to corrosion, moisture, mud and other contaminants often found in the field where the winches are typically used. The advantage of the manual switch of this invention is that it minimizes the number of external connections necessary in conventional winch systems and provides a sealed housing filled with a contact fluid which prevents foreign matter, air and moisture from degrading the switch contact life. The manual switch of this invention is thus capable of manually operating a winch under circumstances where the conventional winch solenoid or electrical system fails, a common occurrence in the field. The manual switch may be mounted either directly on the winch motor by means of bus bar straps or connected remotely by means of wire leads. Alternatively, the switch can be configured in the winch frame itself, as desired. Furthermore, the manual switch of this invention can be configured in a manual-only mode by implementing a hand-operated, handle-turret assembly or it can be remotely operated by means of a pair of U-control wires connected to a bracket mounted on a rotatable turret attached to the switch housing, to distance the operator from the wire rope or cable in the winch in case the cable fails. Similar remote electrical operation can be effected by means of a pair of solenoids or a rotary actuator mounted on the winch housing and connected to the internal movable contact bars to effect the desired forward and reverse operation of the direct current reversible winch motor.
2. Description of the Prior Art
Various types of electric winches and hoists are known in the art. U.S. Pat. No. 1,945,712, dated Feb. 6, 1934, to R. J. Wadd, details a "Hoist" wherein the major elements of the hoist, which include the motor, wire rope, drum and reduction gearing between the motor and drum, are so closely and advantageously organized as to provide for a smooth and easy application of power of the motor to the drum in a balanced manner to prolong the life of the hoist and insure long term satisfactory and efficient operation. U.S. Pat. No. 2,274,280, dated Feb. 24, 1942, to K. W. Stinson details a hoist having a mechanical contrivence located between the control lever and the controller switch, such that in event that the control cords attached to the lever are too quickly operated in the act of reversing rotation of the motor shaft, the control mechanism will be temporarily locked for a period of time sufficient to permit the motor to come to a standstill. U.S. Pat. No. 2,301,678, dated Nov. 10, 1942, to C. Brongersma, details a "Controller Actuator" which embodies novel centrifugal weight and stop arrangements, such that the weight will be jammed against the stop to prevent full throw of the controller from one extreme position to the other except when the controller has shifted slowly. An "Electric Winch Apparatus" is detailed in U.S. Pat. No. 4,556,199, dated Dec. 3, 1985, to Ryan F. Dansie, et al. The device has an alternating current motor and direct current operable clutch and brake coils, together with a control circuit for energizing the apparatus. The control circuit includes alternating current switching of DC current flows, operator control of both reeling in and unreeling drum functions and selected use of separate brake release and brake hold-off coils, with a combination of full-wave and half-wave energizing currents. U.S. Pat. No. 4,789,135, dated Dec. 6, 1988, to H. Watanabe, details an "Operating Device For Electric Hoist". The device has a DC motor for raising and lowering an object and includes a low speed adjusting setting unit and a high speed adjusting setting unit provided in a control box. The operating device further includes a two-step push button switch for the raising operation, for switching over the low speed adjusting setting unit and the high speed adjusting setting unit to connect either of the units to a speed-change control circuit by pushing the two-step push button switch to either a first or a second step position. A second two-step push button switch energizes the lowering operation for switching over the low speed adjusting setting and the high speed adjusting setting units. U.S. Pat. No. 5,167,400, dated Dec. 1, 1992, to G. Anthoine, details a "Control Device For Lifting Winches, In Particular for Drilling Rigs". The control device includes a control circuit that facilitates controlled excitation of an electric motor. A manipulator on a control panel controls the control circuit by establishing, according to its position, a given speed request instruction. An indexing circuit for controlling the control circuit is adapted on the basis of predetermined end-of-travel positions and in accordance with a given law relating the speed to the difference in height between a given end of travel position and the actual height of the time in question, to establish a given speed request instruction. A comparator passes to the control circuit only the speed request instruction that it receives representing the lowest speed.
It is an object of this invention to provide a new and improved manual switch for direct current, reversible electric winches, which manual switch is designed to mount on or in the winch housing of the electric winch or electrically connect to the reversible DC motor in the electric winch to operate the DC electric motor in the forward and reverse directions exclusive of the conventional operating switches and electrical components of the winch.
Another object of this invention is to provide a new and improved manual winch switch which is characterized by a sealed switch housing mounted on or in the winch housing of an electric winch and connected to the DC reversible winch motor for operating the winch motor in the event of failure of the conventional electrical winch-operating system.
Yet another object of this invention is to provide a manual switch for mounting on or in a conventional DC electric winch housing and electrically connected to the reversible DC electric motor in the winch for manually operating the winch by hand-manipulation of a turret handle or push-pull knobs attached to the switch housing or remotely operating the switch by manipulation of a control handle connected to the switch housing by means of wires or by energizing a rotary actuator or solenoids mounted in the switch housing.
Another object of this invention is to provide a new and improved sealed, substantially fail-safe manual switch for operating a winch in the event of failure of the conventional winch electrical system, which manual switch includes a switch housing containing spring-loaded contact bars as well as fixed contacts insulated from the housing and from each other and located in a pool of contact fluid sealed in the housing, wherein the fixed contacts in the housing are connected to the reversible DC electric winch motor and the spring-loaded contact bars within the housing are selectively manipulated by hand-operation of a turret assembly or push-pull knobs mounted on the switch housing or by a remote handle connected to the fixed housing by means of wires or by means of a rotary actuator or a pair of solenoids mounted on the housing and connected to the contact bars and operated by a toggle switch, to operate the reversible DC electric winch motor when the conventional winch electrical system fails.

Manual switch for direct current reversible electric winch motors


A process for increasing the yield of C10 plus hydrocarbon products from a Fischer-Tropsch plant which comprises (a) recovering a Fischer-Tropsch condensate fraction boiling below about 700 degrees F. from the Fischer-Tropsch plant, wherein said fraction contains at least 10 weight percent and preferably more olefins; (b) contacting the olefins in the Fischer-Tropsch condensate fraction under oligomerization conditions, at a reaction temperature between about 650 degrees F. and 800 degrees F. with an oligomerization catalyst comprising active chromium on an inert support; and (c) recovering a C10 plus hydrocarbon product.

The invention relates to a process for upgrading Fischer-Tropsch products by increasing the yield of diesel and lubricating base oils through the oligomerization of olefins in the condensate using a chromium catalyst and high temperature.
Products prepared from the Fischer-Tropsch process comprise a mixture of various solid, liquid, and gaseous hydrocarbons. Those Fischer-Tropsch products which boil within the range of lubricating base oil and diesel are usually of higher value than lower boiling products, such as naphtha, or normally gaseous products, such as LPG. Obviously, it is advantageous to capture the carbon value of the lower boiling and normally gaseous products by upgrading them to higher molecular weight and higher value products.
High quality lubricating base oils may be prepared from the Fischer-Tropsch wax recovered as one of the products of the Fischer-Tropsch synthesis. A process for upgrading the other hydrocarbon products recovered from the Fischer-Tropsch process into suitable feedstocks for preparing high quality lubricating base oils is highly desirable. Lubricating base oils typically will have an initial boiling point above about 315 degrees C. (600 degrees F.). High quality diesel products also may be prepared from the syncrude recovered from the Fischer-Tropsch process. Fischer-Tropsch derived diesel typically has very low sulfur and aromatics content and an excellent cetane number. These qualities make Fischer-Tropsch derived diesel an excellent blending stock for upgrading lower quality petroleum-derived diesel. Accordingly, it is desirable to be able to maximize the yields of such higher value hydrocarbon products which boil within the range of lubricating base oils and diesel. At the same time, it is desirable to minimize the yields of lower value products, such as naphtha, and C4 minus products.
All syncrude Fischer-Tropsch products as they are initially recovered from the Fischer-Tropsch reactor contain varying amounts of olefins depending upon the type of Fischer-Tropsch operation employed. In addition, the crude Fischer-Tropsch product also contains a certain amount of oxygenated hydrocarbons, especially alcohols, which are reported to act as poisons to most oligomerization catalysts. In conventional processes, these oxygenates may be removed through a hydrotreating step, or, alternatively, they may be readily converted to olefins by a dehydration step. The olefins originally present in the Fischer-Tropsch products or derived from converted oxygenates may be oligomerized to yield hydrocarbons having a higher molecular weight than the original feed. The oligomerization of olefins has been well reported in the literature and a number of commercial processes are available. See, for example, U.S. Pat. Nos. 4,417,088; 4,827,064; 4,827,073, and 4,990,709. Oligomerization also introduces desirable branching into the hydrocarbon molecule which lowers the pour point of the diesel and lubricating base oil products, thereby improving the cold flow properties of the product. See for example U.S. Pat. No. 4,417,088. The use of chromium as the active metal in the oligomerization catalyst has been described in the literature. See, for example U.S. Pat. Nos. 4,827,073; 4,990,709, and 5,264,642. However, the maximum temperature under which the oligomerization reaction will proceed without promoting undesired side reactions has been reported to be about 480 degrees F. (250 degrees C.).
Fischer-Tropsch wax refers to a high boiling fraction from the Fischer-Tropsch derived syncrude and is most often a solid at room temperature. For the purpose of this disclosure xe2x80x9cFischer-Tropsch waxxe2x80x9d will be contained in the higher boiling portion of the Fischer-Tropsch syncrude and will have an initial boiling point approximately the same as that for lubricating base oil, i.e., above about 315 degrees C. (600 degrees F.). The term xe2x80x9cFischer-Tropsch condensatexe2x80x9d refers in this disclosure to that fraction of the Fischer-Tropsch syncrude which is normally liquid at ambient temperature. Accordingly, the Fischer-Tropsch condensate fraction is that fraction which includes those hydrocarbons generally having five or more carbon atoms in their molecular structure but having a lower boiling range than Fischer-Tropsch wax.
As used in this disclosure, the term xe2x80x9cC19 minus Fischer-Tropsch productxe2x80x9d refers to a product recovered from a Fischer-Tropsch reaction zone which is predominantly comprised of hydrocarbons having 19 carbon atoms or less in the molecular structure. One skilled in the art will recognize that such products may actually contain a significant amount of hydrocarbons containing greater than 19 carbon atoms. In general, what is referred to are those hydrocarbons having a boiling range of diesel and below. In general, for the purposes of this disclosure, diesel is considered as having an upper boiling point of about 700 degrees F. (370 degrees C.) and an initial boiling point of about 300 degrees F. (about 150 degrees C.). Diesel may also be referred to as C10 to C19 hydrocarbons. Likewise, Fischer-Tropsch wax preferably is comprised predominantly of xe2x80x9cC20 plus productxe2x80x9d and refers to a product comprising primarily hydrocarbons having 20 or more carbon atoms in the structure of the molecule. C20 plus product will have an initial boiling point at the upper end of the boiling range for diesel, i.e., above about 600 degrees F. (315 degrees C.). It should be noted that the upper end of the boiling range for diesel and the lower end of the boiling range for Fischer-Tropsch wax have considerable overlap. The term xe2x80x9cnaphthaxe2x80x9d when used in this disclosure refers to a liquid product having between about C5 to about C9 carbon atoms in the molecular structure and will have a boiling range generally below that of diesel but wherein the upper end of the boiling range will overlap that of the initial boiling point of diesel. The term C10 plus hydrocarbons refers to those hydrocarbons generally boiling above the range of naphtha, i.e., the fractions boiling within the range of diesel and lubricating base oils or above about 150 degrees C. Products recovered from the Fischer-Tropsch synthesis which are normally in the gaseous phase at ambient temperature are referred to as C4 minus product in this disclosure. LPG which is primarily a mixture of propane and butane is an example of a C4 minus product. The precise cut-point selected for each of the products in carrying out the distillation operation will be determined by the product specifications and yields desired.
As used in this disclosure the word xe2x80x9ccomprisesxe2x80x9d or xe2x80x9ccomprisingxe2x80x9d is intended as an open-ended transition meaning the inclusion of the named elements, but not necessarily excluding other unnamed elements. The phrase xe2x80x9cconsists essentially ofxe2x80x9d or xe2x80x9cconsisting essentially ofxe2x80x9d is intended to mean the exclusion of other elements of any essential significance to the composition. The phrase xe2x80x9cconsisting ofxe2x80x9d or xe2x80x9cconsists ofxe2x80x9d are intended as a transition meaning the exclusion of all but the recited elements with the exception of only minor traces of impurities.
The present invention is directed to a process for increasing the yield of C10 plus hydrocarbon products from a Fischer-Tropsch plant which comprises (a) recovering a Fischer-Tropsch condensate fraction boiling below about 700 degrees F. from the Fischer-Tropsch plant, wherein said fraction contains at least 10 weight percent olefins; (b) contacting the olefins in the Fischer-Tropsch condensate fraction under oligomerization conditions, at a reaction temperature between about 650 degrees F. and 800 degrees F. with an oligomerization catalyst comprising active chromium on an inert support; and (c) recovering a C10 plus hydrocarbon product having a higher average molecular weight than the Fischer-Tropsch condensate. The amount of olefins present in the Fischer-Tropsch condensate fraction will vary depending on the way in which the Fischer-Tropsch synthesis is carried out. From an economic perspective the more olefins present, the more C10 plus product will be recovered. Preferably, the condensate fraction will contain at least 20 percent olefins by weight; more preferably, at least 30 percent olefins by weight; and most preferably, at least 50 percent olefins by weight.
Almost all Fischer-Tropsch syncrudes contain a certain amount of oxygenates. In conventional oligomerization processes, the oxygenates will act as a catalyst poison and must either be removed or converted into olefins prior to the oligomerization step. In the present invention the oxygenates need not be converted or removed prior to oligomerization, since it has been found that the oxygenates will not deactivate the chromium catalyst under the conditions of the process. Surprisingly, it has been discovered that the presence of oxygenates has no significant detrimental effect on catalyst activity when the process is carried out according to the invention. The present process may be carried out in the presence of 10 weight percent and even 20 weight percent oxygenates.
In the Fischer-Tropsch synthesis process, liquid and gaseous hydrocarbons are formed by contacting a synthesis gas (syngas) comprising a mixture of hydrogen and carbon monoxide with a Fischer-Tropsch catalyst under suitable temperature and pressure reactive conditions. The Fischer-Tropsch reaction is typically conducted at temperatures of from about 300 degrees to about 700 degrees F. (149 degrees to 371 degrees C.) preferably from about 400 degrees to about 550 degrees F. (204 degrees to 228 degrees C.); pressures of from about 10 to about 600 psia, (0.7 to 41 bars) preferably 30 to 300 psia, (2 to 21 bars) and catalyst space velocities of from about 100 to about 10,000 cc/g/hr., preferably 300 to 3,000 cc/g/hr.
The products from the Fischer-Tropsch synthesis may range from C1 to C200 plus hydrocarbons with a majority in the C5-C100 plus range. The reaction can be conducted in a variety of reactor types, such as, for example, fixed bed reactors containing one or more catalyst beds, slurry reactors, fluidized bed reactors, or a combination of different type reactors. Such reaction processes and reactors are well known and documented in the literature. The slurry Fischer-Tropsch process, which is preferred in the practice of the invention, utilizes superior heat (and mass) transfer characteristics for the strongly exothermic synthesis reaction and is able to produce relatively high molecular weight, paraffinic hydrocarbons when using a cobalt catalyst. In the slurry process, a syngas comprising a mixture of hydrogen and carbon monoxide is bubbled up as a third phase through a slurry which comprises a particulate Fischer-Tropsch type hydrocarbon synthesis catalyst dispersed and suspended in a slurry liquid comprising hydrocarbon products of the synthesis reaction which are liquid at the reaction conditions. The mole ratio of the hydrogen to the carbon monoxide may broadly range from about 0.5 to about 4, but is more typically within the range of from about 0.7 to about 2.75 and preferably from about 0.7 to about 2.5. A particularly preferred Fischer-Tropsch process is taught in EP0609079, also completely incorporated herein by reference for all purposes.
Suitable Fischer-Tropsch catalysts comprise one or more Group VIII catalytic metals such as Fe, Ni, Co, Ru and Re, with cobalt being preferred. Additionally, a suitable catalyst may contain a promoter. Thus, a preferred Fischer-Tropsch catalyst comprises effective amounts of cobalt and one or more of Re, Ru, Pt, Fe, Ni, Th, Zr, Hf, U, Mg and La on a suitable inorganic support material, preferably one which comprises one or more refractory metal oxides. In general, the amount of cobalt present in the catalyst is between about 1 and about 50 weight percent of the total catalyst composition. The catalysts can also contain basic oxide promoters such as ThO2, La2O3, MgO, and TiO2, promoters such as ZrO2, noble metals (Pt, Pd, Ru, Rh, Os, Ir), coinage metals (Cu, Ag, Au), and other transition metals such as Fe, Mn, Ni, and Re. Suitable support materials include alumina, silica, magnesia and titania or mixtures thereof. Preferred supports for cobalt containing catalysts comprise titania. Useful catalysts and their preparation are known and illustrated in U.S. Pat. No. 4,568,663, which is intended to be illustrative but non-limiting relative to catalyst selection.
As already noted, all Fischer-Tropsch syncrude contains olefins with the amount dependent to some extent on the way in which the Fischer-Tropsch synthesis is conducted. In the present invention, it is advantageous to conduct the Fischer-Tropsch synthesis in a way that maximizes the production of olefins in the condensate fraction. Preferably the olefins will comprise at least 20 weight percent of the condensate fraction, more preferably at least 30 weight percent, and most preferably at least 50 weight percent. Most Fischer-Tropsch syncrudes also contain a certain amount of oxygenates, mostly alcohols. Although unlike some prior art processes these oxygenates do not need to be removed in the present process, it may be advantageous to convert the alcohols into olefins prior to oligomerization.
In some Fischer-Tropsch syncrude, oxygenates may comprise greater than 10 weight percent of the total. The presence of more than 15 weight percent oxygenates in the condensate fraction is not unusual. If desired, the alcohols in the feed may be dehydrated to convert them into olefins prior to the oligomerization step by processing the feedstock over a catalyst, typically gamma alumina. The dehydration of alcohols to olefins is discussed in Chapter 5, xe2x80x9cDehydrationxe2x80x9d in Catalytic Processes and Proven Catalysts by Charles L. Thomas, Academic Press, 1970.
The present invention is intended to maximize the yield of heavy products, especially lubricating base oils and diesel, by oligomerizing the olefins in the Fischer-Tropsch condensate and those olefins, if any, produced by the dehydration of alcohols. During oligomerization the lighter olefins are converted into heavier products. The carbon structure of the oligomers will also display branching at the points of molecular addition. Due to the introduction of branching into the molecule, the pour point properties of the products are enhanced making the final products of the oligomerization operation excellent candidates for blending components to upgrade lower quality conventional petroleum-derived products to meet market specifications.
Preferably, the oligomerized product will have an average molecular weight at least 10 percent higher than the initial feedstock, preferably at least 20 percent higher. Although the oligomerization reaction will proceed over a wide range of conditions, with the present invention the temperature is maintained between about 650 degrees F. (343 degrees C.) and about 800 degrees F. (427 degrees C.), with temperatures within the range of from about 700 degrees F. (371 degrees C.) and about 775 degrees F. (413 degrees C.) being preferred. The oligomerization reaction may be conducted in either a batch-type reactor or in a fixed-bed continuous flow reactor. A fixed-bed, continuous flow reactor is usually preferred. Other oligomerization conditions include a space velocity from 0.1 to 3 LHSV and a pressure from 0 to 2000 psig.
The catalyst used in carrying out the process of the present invention comprises active chromium on a high surface area support. A complete description of the catalyst which may be used to carry out the invention and its method of preparation may be found in U.S. Pat. No. 4,827,073. The active component of the catalyst is chromium which is preferably present in a lower valence state. Although the valence of the active chromium is not certain, the active form is believed to be chromium II. However, the inventors do not wish to be bound by the exact oxidation state of the chromium in describing the invention.
It is important that the chromium be highly dispersed on the support. Preferred support materials include silica, alumina, titania, silica alumina, and magnesium, with silica being especially preferred. The support should be a porous material preferably having an average pore opening between about 40 Angstroms and about 350 Angstroms, more preferably with an average pore opening between about 60 Angstroms and about 300 Angstroms. Silica supports having an average pore diameter of about 150 Angstrom units have been found to give especially satisfactory results when used to carry out the oligomerization step. Typically the chromium is impregnated on the porous support using procedures well known to those skilled in the art. After the active metal is impregnated onto the support the catalyst is dried and calcined. In the finished catalyst, the chromium will usually be present in an amount within the range from about 0.2 weight percent to about 5 weight percent, with an amount between about 0.5 weight percent and about 2 weight percent being preferred. The catalyst usually must be reduced to activate the metal prior to use. Methods for reducing the chromium to its active form have been well described in the literature. Generally, a reducing gas such as carbon monoxide or hydrogen is passed over the catalyst.
The oligomerization product recovered from the oligomerization operation will usually be further processed in order to meet the specifications for the final product. The additional processing may be intended to improve the cold flow properties of the product by means of a dewaxing operation or to improve its oxidation stability by means of a hydrofinishing operation. The dewaxing of the oligomerization product is preferably carried out as a catalytic hydroisomerization step in order to minimize the wax cracking which reduces the yield of the higher molecular weight products.
Catalytic hydroisomerization is intended to achieve high conversion levels of wax to non-waxy iso-paraffins while at the same time minimizing the conversion by cracking. Since wax conversion can be complete, or at least very high, this process typically does not need to be combined with additional dewaxing processes to produce a lubricating oil base stock with an acceptable pour point. Isomerization operations suitable for use with the present invention typically uses a catalyst comprising an acidic component and may optionally contain an active metal component having hydrogenation activity. The acidic component of the catalysts preferably includes an intermediate pore SAPO, such as SAPO-11, SAPO-31, and SAPO41, with SAPO-11 being particularly preferred. Intermediate pore zeolites, such as ZSM-22, ZSM-23, SSZ-32, ZSM-35, and ZSM48, also may be used in carrying out the isomerization. Typical active metals include molybdenum, nickel, vanadium, cobalt, tungsten, zinc, platinum, and palladium. The metals platinum and palladium are especially preferred as the active metals, with platinum most commonly used.
The phrase xe2x80x9cintermediate pore sizexe2x80x9d, when used herein, refers to an effective pore aperture in the range of from about 5.3 to about 6.5 Angstrom when the porous inorganic oxide is in the calcined form. Molecular sieves having pore apertures in this range tend to have unique molecular sieving characteristics. Unlike small pore zeolites such as erionite and chabazite, intermediate pore zeolites will allow hydrocarbons having some branching into the molecular sieve void spaces. Unlike larger pore zeolites such as faujasites and mordenites, they are able to differentiate between n-alkanes and slightly branched alkenes, and larger alkanes having, for example, quaternary carbon atoms. See U.S. Pat. No. 5,413,695. The term xe2x80x9cSAPOxe2x80x9d refers to a silicoaluminophosphate molecular sieve such as described in U.S. Pat. Nos. 4,440,871 and 5,208,005.
In preparing those catalysts containing a non-zeolitic molecular sieve and having a hydrogenation component, it is usually preferred that the metal be deposited on the catalyst using a non-aqueous method. Non-zeolitic molecular sieves include tetrahedrally-coordinated [AlO2] and [PO2] oxide units which may optionally include silica. See U.S. Pat. No. 5,514,362. Catalysts containing non-zeolitic molecular sieves, particularly catalysts containing SAPO""s, on which the metal has been deposited using a non-aqueous method have shown greater selectivity and activity than those catalysts which have used an aqueous method to deposit the active metal. The non-aqueous deposition of active metals on non-zeolitic molecular sieves is taught in U.S. Pat. No. 5,939,349. In general, the process involves dissolving a compound of the active metal in a non-aqueous, non-reactive solvent and depositing it on the molecular sieve by ion exchange or impregnation.
Hydrofinishing operations are intended to improve the UV stability and color of the products. Unsaturated bonds remaining in the Fischer-Tropsch product will be hydrogenated in the hydrofinishing operation. A general description of the hydrofinishing process may be found in U.S. Pat. Nos. 3,852,207 and 4,673,487. As used in this disclosure, the term UV stability refers to the stability of the lubricating base oil or other products when exposed to ultraviolet light and oxygen. Instability is indicated when a visible precipitate forms or darker color develops upon exposure of the product to ultraviolet light and air which results in a cloudiness or floc. Lubricating base oils and diesel products prepared by the process of the present invention generally will require UV stabilization before they are suitable for use in the manufacture of commercial lubricating oils and marketable diesel.
In the present invention, the total pressure in the hydrofinishing zone will be above 500 psig, preferably above 1000 psig, and most preferably will be above 1500 psig. The maximum total pressure is not critical to the process, but due to equipment limitations the total pressure will not exceed 3000 psig and usually will not exceed about 2500 psig. Temperature ranges in the hydrofinishing zone are usually in the range of from about 300 degrees F. (150 degrees C.) to about 700 degrees F. (370 degrees C.), with temperatures of from about 400 degrees F. (205 degrees C.) to about 500 degrees F. (260xc2x0 C.) being preferred. The LHSV is usually within the range of from about 0.2 to about 2.0, preferably 0.2 to 1.5, and most preferably from about 0.7 to 1.0. Hydrogen is usually supplied to the hydrofinishing zone at a rate of from about 1000 to about 10,000 SCF per barrel of feed. Typically, the hydrogen is fed at a rate of about 3000 SCF per barrel of feed.
Suitable hydrofinishing catalysts typically contain a Group VIII noble metal component together with an oxide support. Metals or compounds of the following metals which are contemplated as useful in hydrofinishing catalysts include ruthenium, rhodium, iridium, palladium, platinum, and osmium. Preferably, the metal or metals will be platinum, palladium or mixtures of platinum and palladium. The refractory oxide support usually consists of silica-alumina, silica-alumina-zirconia, and the like. Typical hydrofinishing catalysts are disclosed in U.S. Pat. Nos. 3,852,207; 4,157,294 and 4,673,487.

Process for the oligomerization of olefins in Fischer-Tropsch condensate using chromium catalyst and high temperature


There is provided a new nonwoven material for personal care products made of fibers, binder in an amount between 1 and 6 weight percent and superabsorbent in an amount between 1 and 80 weight percent, where the superabsorbent is contained in micro-pockets in the nonwoven. These micro-pockets may be made by creping a nonwoven fabric, orienting fibers in the Z-direction, and by passing a relatively lofty nonwoven fabric between unheated thermal pattern bond and anvil rolls. These materials exhibit good permeability to liquid in the pre- and post-wetted conditions, thus avoiding gel blocking and other negative effects of superabsorbent swelling within a fabric. Such a fibrous material is useful in personal care products, like diapers, training pants, incontinence garments and feminine hygiene products.

The present invention concerns formed materials mainly for personal care products like diapers, training pants, swim wear, absorbent underpants, adult incontinence products and feminine hygiene products. This material may also be useful for other applications such as, for example, in bandages and wound dressings, nursing pads and in veterinary and mortuary applications.
Personal care articles usually have multiple layers of material of some sort to absorb liquids from the body. These layers may include natural fibers, synthetic fibers and superabsorbent particles in varying proportions. When liquid such as urine is deposited into a personal care product like a diaper, it goes through the uppermost layers, typically a liner against the body and a xe2x80x9csurgexe2x80x9d or xe2x80x9cintakexe2x80x9d layer designed to provide temporary liquid holding capacity. The product may also have a xe2x80x9cdistributionxe2x80x9d layer designed to move liquid in the X and Y directions in order to utilize more of the absorbent core. After going through these upper layers, the urine enters the absorbent core portion of the product. The absorbent core permanently retains the liquid.
The functions of the layers mentioned above may each be performed by different layers or a layer may perform more than one function. The combination of more than one function in a single layer, however, generally results in a significant decrease in the performance of each of the functions.
Absorbent cores are typically composed of superabsorbent particles and/or pulp. A newer class of absorbents also uses a binder to improve wet stability and to ease converting into final products. Binders can be liquid adhesive or thermally activatable fibers typically present in amounts between 10 and 25 weight percent.
Superabsorbent particles absorb many times their weight in liquid and swell greatly as a result of being wetted. This swelling holds liquid within the product and so protects the wearer""s skin, clothing and bedding, but may also block the further intake of liquid. This occurs because the swollen particles become so large as to close off fluid entrances to the structure, a phenomenon known in the art as xe2x80x9cgel blockingxe2x80x9d.
Alternatively, an absorbent structure lacking superabsorbent and made of the traditional pulp and binder fiber can experience xe2x80x9cwet collapsexe2x80x9d. This occurs as a result of saturation of the pulp and the subsequent inability to regenerate void space as fluid is added to the structure. The binder fibers, generally synthetic polymer fibers that are naturally hydrophobic, contribute to this problem since they interfere with the wicking performance of the structure due to their poor wettability. In addition, the constraints induced by the bonding of the binder fibers restrains expansion of the absorbent structure, further reducing void volume and decreasing the ultimate capacity of the material. If the structure were able to wick fluid away from the area of incipient wet collapse more efficiently, the phenomenon might be avoided completely.
A material which treads the fine line between wet collapse and gel blocking would be very desirable. Such a material would avoid the undesirable features of uncontrolled superabsorbent expansion while efficiently absorbing fluids. It would also avoid wet collapse by maintaining a sufficient pore structure, allowing liquid to continue moving through it. Such a material would exhibit high levels of multi-functional absorbent performance.
In response to the discussed difficulties and problems encountered in the prior art, a new structural composite comprising nonwoven fabric to which has been added superabsorbent has been developed. The superabsorbent is preferably in the form of particles (SAP). The SAP is placed in xe2x80x9cmicro-pocketsxe2x80x9d formed by various means like creping or the manual creation of depressions in the surface of the nonwoven using a pattern roll. The volume of the micro-pockets may be between 0.33 and 10 cubic millimeters. The SAP need not be uniformly placed in the web but may be located in a non-uniform manner across the width of the fabric. As a result of this construction, the nonwoven web remains permeable to liquids before and after wetting. When the web is wetted, the superabsorbent is free to swell without disrupting the fibrous network of the web since it is located in the discrete pockets. The web should have a permeability above 1500 darcys and preferably above 2000 darcys.
In this invention, at least one layer having a mixture of polymeric fibers, superabsorbent in an amount between 1 and 80 weight percent and binder in an amount between 1 and 6 weight percent is provided. More particularly, amounts of superabsorbent between 25 and 75 weight percent and still more particularly between 40 and 60 percent may be beneficial. Additional layers may be present as well and the inventive layer may be placed in a personal care product to act as a distribution and absorption layer. The inventive layer has good distribution properties, presumably due to the avoidance of gel blocking, capillary disruption and wet collapse, by virtue of the discrete placement of the superabsorbent. It is also possible to electrically treat the web of this invention to improve particle adherence.
These materials are suitable for use in personal care products like diapers, training pants, incontinence products, bandages, and sanitary napkins.
As used herein the term xe2x80x9cnonwoven fabric or webxe2x80x9d means a web having a structure of individual fibers or threads which are interlaid, but not in an identifiable manner as in a knitted fabric. Nonwoven fabrics or webs have been formed from many processes such as for example, meltblowing processes, spunbonding processes, and bonded carded web processes. The basis weight of nonwoven fabrics is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm) and the fiber diameters useful are usually expressed in microns. (Note that to convert from osy to gsm, multiply osy by 33.91).
xe2x80x9cSpunbonded fibersxe2x80x9d refers to small diameter fibers that are formed by extruding molten thermoplastic material as filaments from a plurality of fine capillaries of a spinneret. Such a process is disclosed in, for example, U.S. Pat. No. 4,340,563 to Appel et al. and U.S. Pat. No. 3,802,817 to Matsuki et al. The fibers may also have shapes such as those described, for example, in U.S. Pat. No. 5,277,976 to Hogle et al. which describes fibers with unconventional shapes.
xe2x80x9cBonded carded webxe2x80x9d refers to webs that are made from staple fibers which are sent through a combing or carding unit, which separates or breaks apart and aligns the staple fibers in the machine direction to form a generally machine direction-oriented fibrous nonwoven web. This material may be bonded together by methods that include point bonding, through air bonding, ultrasonic bonding, adhesive bonding, etc.
As used herein, the term xe2x80x9ccoformxe2x80x9d means a process in which at least one meltblown diehead is arranged near a chute through which other materials are added to the web while it is forming. Such other materials may be pulp, superabsorbent particles, natural fibers (for example, rayon or cotton fibers) and/or synthetic fibers (for example, polypropylene or polyester) fibers, for example, where the fibers may be short cut of staple length. Coform processes are shown in commonly assigned U.S. Pat. No. 4,818,464 to Lau and U.S. Pat. No. 4,100,324 to Anderson et al. Webs produced by the coform process are generally referred to as coform materials.
xe2x80x9cAirlayingxe2x80x9d is a well-known process by which a fibrous nonwoven layer can be formed. In the airlaying process, bundles of small fibers having typical lengths ranging from about 3 to about 52 millimeters (mm) are separated and entrained in an air supply and then deposited onto a forming screen, usually with the assistance of a vacuum supply. The randomly deposited fibers then are bonded to one another using, for example, hot air to activate a binder component or a latex adhesive. Airlaying is taught in, for example, U.S. Pat. No. 4,640,810 to Laursen et al., and U.S. Pat. No. 5,885,516 to Christensen.
The term xe2x80x9ccrepingxe2x80x9d means a process for folding a web such that loops are created in the web structure. Such loops define an arch, semi-circle or similar configuration extending above the plane of the uncreped nonwoven web, and terminating at both ends in the nonwoven web. Examples of creped materials and methods may be found in U.S. Pat. No. 6,150,002 to Varona and PCT publication WO 00/33780 (U.S. application Ser. No. 09/209,044) to Varona et al. Crepe level (CL) is a measure of creping expressed as a percentage and is calculated as the speed of the creping drum surface (A) minus the speed of the windup reel for the creped web (B) divided by the speed of the creping drum surface (A), multiplied by 100, or: CL=(Axe2x88x92B)/A*100.
xe2x80x9cZ-direction materialsxe2x80x9d refers to fabrics wherein the fibers are predominately oriented in the Z-direction during the formation of the fabric, as opposed to during a post-treatment step like creping. Examples of such materials and methods may be found in PCT publication WO 00/66057 and WO 00/66284, corresponding to U.S. application Ser. Nos. 09/538,744 and 09/537,564, respectively, and both commonly assigned.
The term xe2x80x9cmicro-pocketsxe2x80x9d means small pockets, in the order of a few cubic millimeters or less, formed in a nonwoven web. They must be sufficiently large to allow entry for and provide storage for superabsorbent particles.
As used herein xe2x80x9cthermal point bondingxe2x80x9d involves passing a fabric or web of fibers to be bonded between a heated calender roll and an anvil roll. The calender roll is usually, though not always, patterned in some way so that the entire fabric is not bonded across its entire surface, and the anvil roll is usually flat. As a result, various patterns for calender rolls have been developed for functional as well as aesthetic reasons. One example of a pattern has points and is the Hansen Pennings or xe2x80x9cHandPxe2x80x9d pattern with about a 30% bond area with about 200 bonds/square inch as taught in U.S. Pat. No. 3,855,046 to Hansen and Pennings. The HandP pattern has square point or pin bonding areas wherein each pin has a side dimension of 0.038 inches (0.965 mm), a spacing of 0.070 inches (1.778 mm) between pins, and a depth of bonding of 0.023 inches (0.584 mm). The resulting pattern has a bonded area of about 29.5%. Another typical point bonding pattern is the expanded Hansen Pennings or xe2x80x9cEHPxe2x80x9d bond pattern which produces a 15% bond area with a square pin having a side dimension of 0.037 inches (0.94 mm), a pin spacing of 0.097 inches (2.464 mm) and a depth of 0.039 inches (0.991 mm). Another typical point bonding pattern designated xe2x80x9c714xe2x80x9d has square pin bonding areas wherein each pin has a side dimension of 0.023 inches, a spacing of 0.062 inches (1.575 mm) between pins, and a depth of bonding of 0.033 inches (0.838 mm). The resulting pattern has a bonded area of about 15%. Yet another common pattern is the C-Star pattern which has a bond area of about 16.9%. The C-Star pattern has a cross-directional bar or xe2x80x9ccorduroyxe2x80x9d design interrupted by shooting stars. Other common patterns include a diamond pattern with repeating and slightly offset diamonds with about a 16% bond area and a wire weave pattern looking as the name suggests, e.g. like a window screen, with about a 19% bond area. Typically, the percent bonding area varies from around 10% to around 30% of the area of the fabric laminate web. As in well known in the art, the spot bonding holds the laminate layers together as well as imparts integrity to each individual layer by bonding filaments and/or fibers within each layer.
As used herein, through-air bonding or xe2x80x9cTABxe2x80x9d means a process of bonding a nonwoven bicomponent fiber web in which hot air is forced through the web. The temperature of the air is sufficient to melt one of the polymers of which the fibers are made. The air velocity is usually between 100 and 500 feet per minute and the dwell time may be as long as 6 seconds. The melting and resolidification of the polymer provides bonding. Through-air bonding (TAB) requires the melting of at least one component to accomplish bonding, so it is usually restricted to webs with two components like conjugate fibers or those which include an adhesive. In the through-air bonder, air having a temperature above the melting temperature of one component and below the melting temperature of another component is directed from a surrounding hood, through the web, and into a perforated drum supporting the web. Alternatively, the through-air bonder may be a flat arrangement wherein the air is directed vertically downward onto the web. The operating conditions of the two configurations are similar, the primary difference being the geometry of the web during bonding. The hot air melts the lower melting polymer component and thereby forms bonds between the filaments to integrate the web.
xe2x80x9cPersonal care productxe2x80x9d means diapers, training pants, swim wear, absorbent underpants, adult incontinence products, bandages and feminine hygiene products. It may further encompass veterinary and mortuary products.
Basis Weight
A circular sample of 3 inches (7.6 cm) diameter is cut and weighed using a balance. Weight is recorded in grams. The weight is divided by the sample area. Five samples are measured and averaged.
Material Caliper (Thickness)
The caliper of a material is a measure of thickness and is measured at 0.05 psi (3.5 g/cm2) with a STARRET(copyright) bulk tester, in units of millimeters. Samples are cut into 4 inch by 4 inch (10.2 cm by 10.2 cm) squares and five samples are tested and the results averaged.
Density
The density of the materials is calculated by dividing the weight per unit area of a sample in grams per square meter (gsm) by the material caliper in millimeters (mm). The caliper should be measured at 0.05 psi (3.5 g/cm2) as mentioned above. The result is multiplied by 0.001 to convert the value to grams per cubic centimeter (g/cc). A total of five samples would be evaluated and averaged for the density values.
Permeability
Permeability (k, in cm2) may be calculated and represents the resistance to flow of a liquid by a material. A liquid of known viscosity (xcex7, in Pascal-sec) is forced through the material of given thickness (t, in cm) at a constant flow rate (v, in cm/sec) and the resistance to flow, measured as a pressure drop (xcex94P, in Pascal""s) is monitored. Permeability is calculated using Darcy""s flow equation:
k=vtxcex7/xcex94P
Note that 1 darcy=9.87xc3x9710xe2x88x929 cm2
In a test for permeability, typical parameters are: a velocity of 20 cm/sec, a sample thickness of 20-50 mils and a test liquid having a viscosity of about 6 Pascal-sec.
This invention nonwoven web having superabsorbent contained within micro-pockets. This web has a high permeability and maintains high permeability to liquid flow even after being wetted. A permeability above 1500 darcys, and preferably above 2000 darcys is considered xe2x80x9chighxe2x80x9d.
The nonwoven web of this invention may be made from a number of processes, including airlaying, spunbonding, bonding and carding, meltblowing and coforming. The material may be creped after formation, given Z-direction fiber orientation during formation, or may be a relatively flat nonwoven structure into which micro-pockets are depressed. Additional layers may be added to the structure and it may be included in personal care products.
The volume in the micro-pockets may be calculated relatively easily and is dependent upon the method of making the pockets. One embodiment of this invention is a creped, pre-bonded spunbond fabric. This is typically thermally bonded as it is produced with an EHP or other pattern in with either a square or diamond layout of the bond points (other layouts may be used but the calculations must be modified). As the fabric is creped, bond points will adhere to the creping drum as it is processed, causing the fabric to increase its Z-directional dimension and decrease or shorten in the X-direction. This results the creation of the xe2x80x9cmicro-pocketsxe2x80x9d useful in this invention for holding superabsorbent, which, in the case of creping, are perhaps more readily envisioned as bulges of fiber between the bond points with space created between the fibers to accommodate the SAP. A typical EHP pattern has bond points spaced about 2.464 mm apart (see definition above) in a square or diamond pattern. Upon creping, the distance (a) between bond points decreases approximately by the crepe level (CL) expressed as a percentage and the height of the fabric increases approximately by the crepe level, yielding an area and volume encompassed by any four bond points of:
Area=((100xe2x88x92CL)*a2)/100
Volume for square pattern=area (a*CL)/200
Volume for diamond pattern=area (20 5*a/2*CL)/200
It should be noted that the minor differences between the square and diamond pattern volumes are due to the orientation of the web when it undergoes creping. A square pattern bonded fabric enters the creping apparatus with two edges of a box formed by four bond points in the machine direction (MD) and two in the cross direction (CD). A diamond pattern bonded fabric does not have such an orientation and instead is oriented with the edges of a box formed by four bond points approximately 45 degrees away from either the cross or machine directions. Other bonding patterns may of course be used. In such cases, the correct area and volume must be calculated. This may be done by those skilled in the art and may be aided by standard references such as for example, the CRC Standard Mathematical Tables from the CRC Press of Cleveland, Ohio.
Creping the webs contemplated for the practice of this invention results in volumes of between about 0.33 to 10 cubic mm, more particularly between 0.33 and 5 cubic mm, more particularly between 0.5 and 1 cubic mm and still more particularly between 0.5 and 2 cubic mm.
As one example of this invention, a nonwoven web may be creped at a level of about 40 percent, and tumbled in a drum with superabsorbent particles to make an addition rate of about 50 weight percent. Such an addition of particles would be in all of the micro-pockets in the fabric, i.e., uniformly, assuming the micro-pockets were distributed uniformly. Alternatively, a length of creped fabric could be unwound around a roller or bar in order to open the folds of the creped fabric. As the fabric passes over the roller, superabsorbent particles could be added in a uniform or non-uniform pattern to these folds. Such embodiments are intended to be within the scope of this invention.
Another method of making the web of this invention is to begin with a relatively flat web and pass it between a pattern and anvil roll to create depressions in the fabric. A lofty fabric is preferred for this embodiment since it will allow the fabric to have sufficient depth to provide adequate micro-pockets. Lofty fabrics are preferably bonded in a through-air bonder rather than by thermal point bonding because thermal point bonding tends to compact the fabric as it passes between the rollers. A bicomponent crimped fabric, like, for example, the fabric of U.S. Pat. No. 5,382,400 to Pike, that may be through-air bonded, should work well in the practice of this invention. After formation and bonding, the depressions may be created in the fabric. This may be done, for example, by using unheated thermal point bonding and flat anvil rolls. The unheated pattern roll would not use a pattern that would pass fully through the web but would only depress the web in pre-selected areas. The pattern may be uniform or non-uniform, providing depressions to only certain areas of the web or providing a changing density of depressions to the web. Patterns which may be used for the creation of depression are greatly varied, including those mentioned above for thermal point bonding, like the EHP, HandP and 714 patterns. After the formation of the depressions, superabsorbent may be deposited on the web to fill all or some of the depressions to the degree desired.
In the case of a pattern and anvil roll used to create depressions in a fabric, the calculation to determine the size of the micro-pockets will be dependent upon the size of the pins used in the pattern roll and the depth of penetration of the pins into the fabric. The HandP pattern, if fully inserted into a fabric, produces a micro-pocket with a volume of about 0.544 cubic mm and the EHP a volume of about 0.876 cubic mm, for example.
If the fabric to which the superabsorbent is added is creped, the superabsorbent should remain in place in micro-pockets formed in the folds of the fabric when the fabric resumes its normal position. If the fabric is relatively flat and provided with depressions, an adhesive may be needed to hold the superabsorbent in place. Alternatively, electrostatic charge may be used to encourage the superabsorbent to remain in the depressions by means of differing electrical polarities or potentials.
Electrostatic charging of webs is accomplished by electret treatment which draws particles toward the fabric by virtue of their electrical charge. Electret treatment can be carried out by a number of different techniques. One technique is described in U.S. Pat. No. 5,401,446 to Tsai et al. assigned to the University of Tennessee Research Corporation. Tsai describes a process whereby a web or film is sequentially subjected to a series of electric fields such that adjacent electric fields have substantially opposite polarities with respect to each other. Thus, one side of the web or film is initially subjected to a positive charge while the other side of the web or film is initially subjected to a negative charge. Then, the first side of the web or film is subjected to a negative charge and the other side of the web or film is subjected to a positive charge. Such webs are produced with a relatively high charge density without an attendant surface static electrical charge. The process may be carried out by passing the web through a plurality of dispersed non-arcing electric fields which may be varied over a range depending on the charge desired in the web. The web may be charged at a range of about 1 kVDC/cm to 12 kVDC/cm or more particularly 4 kVDC/cm to 10 kVDC/cm and still more particularly 7 kVDC/cm to about 8 kVDC/cm. Other methods of electret treatment are known in the art such as that described in U.S. Pat. No. 4,215,682 to Kubik et al, U.S. Pat. No. 4,375,718 to Wadsworth, U.S. Pat. No. 4,592,815 to Nakao and U.S. Pat. No. 4,874,659 to Ando.
The fabric used in the practice of this invention may have natural fibers, though webs of synthetic polymer fibers are preferred. An effective amount of binder, typically from 1 to 6 weight percent (based on the web weight before addition of superabsorbent), may be present to help provide mechanical integrity by binding the fibers and particles together. The binder may more particularly be between 1 and 5 percent and still more particularly between 1 and 4 percent. As much as 80 percent by weight of the web may be added as superabsorbent. A more particular range for the superabsorbent is between 25 and 75 weight percent and still more particularly between 40 and 60 weight percent.
Superabsorbents that are useful in the present inventions can be chosen from classes based on chemical structure as well as physical form. These include superabsorbents with low gel strength, high gel strength, surface cross-linked superabsorbents, uniformly cross-linked superabsorbents, or superabsorbents with varied cross-link density throughout the structure. Superabsorbents may be based on chemistries that include poly(acrylic acid), poly(iso-butylene-co-maleic anhydride), poly(ethylene oxide), carboxy-methyl cellulose, poly(vinyl pyrrollidone), and poly(-vinyl alcohol). The superabsorbents may range in swelling rate from slow to fast. The superabsorbents may be in the form of foams, macroporous or microporous particles or fibers, particles or fibers with fibrous or particulate coatings or morphology. The superabsorbents may be in the shape of ribbons, particles, fibers, sheets or films. Superabsorbents in the form of particles are preferred for the practice of this invention. Superabsorbents may be in various length and diameter sizes and distributions. The superabsorbents may be in various degrees of neutralization. Counter-ions are typically Li, Na, K, Ca.
An exemplary superabsorbent was obtained from Stockhausen, Inc and is designated FAVOR(copyright) SXM 880. Another example of these types of superabsorbents may be obtained from the Dow Chemical Company under the name DRYTECH(copyright) 2035. An example of fibrous superabsorbents may be obtained from Camelot Technologies, Ltd., of High River, Alberta, Canada and is designated FIBERDRI(copyright) 1241. Another Example included in these types of superabsorbents is obtained from Chemtall Inc. or Riceboro, Ga., and is designated FLOSORB 60 LADY(copyright), also known as LADYSORB 60(copyright). Additional types of superabsorbents not listed here which are commonly available and known to those skilled in the art can also be useful in the present inventions.
Binders typically used in these structures help provide mechanical integrity and stabilization. Binders include fiber, liquid or other binder means that may be thermally activated. Preferred fibers for inclusion are those having a relative melting point such as polyolefin fibers. Lower melting point polymers provide the ability to bond the fabric together at fiber cross-over points upon the application of heat. In addition, fibers having a lower melting polymer, like conjugate and biconstituent fibers are suitable for practice of this invention. Fibers having a lower melting polymer are generally referred to as xe2x80x9cfusible fibersxe2x80x9d. By xe2x80x9clower melting polymersxe2x80x9d what is meant are those having a glass transition temperature less than about 175xc2x0 C. It should be noted that the texture of the absorbent web can be modified from soft to stiff through selection of the fusion and quenching behavior of the polymer. Exemplary binder fibers include conjugate fibers of polyolefins, polyamides and polyesters. Three suitable binder fibers are sheath core conjugate fibers available from KoSa Inc. (Charlotte, N.C.) under the designation T-255 and T-256, both with a polyolefin sheath, or T-254, which has a low melt co-polyester sheath. Many suitable binder fibers are known to those skilled in the art, and are available by many manufacturers such as Chisso and Fibervisions LLC of Wilmington, Del. A suitable liquid binder is KYMENE(copyright) 557LX available from Hercules Inc. of Wilmington, Del. Other suitable liquid binders include ethylene vinyl acetate emulsion polymers sold by National Starch and Chemical Company (Bridgewater, N.J.) under the tradename DUR-O-SET(copyright) ELITE(copyright) series (including ELITE(copyright) 33 and ELITE(copyright) 22). Other suitable binders are sold by Air Products Polymers and Chemicals under the name AIRFLEX(copyright).
Synthetic fibers include those made from polyolefins, polyamides, polyesters, rayon, acrylics, superabsorbents, TENCEL(copyright) regenerated cellulose and any other suitable synthetic fibers known to those skilled in the art. Synthetic fibers may also include kosmotropes for product degradation.
Many polyolefins are available for fiber production, for example polyethylenes such as Dow Chemical""s ASPUN(copyright) 6811A liner low density polyethylene, 2553 LLDPE and 25355 and 12350 high density polyethylene are such suitable polymers. The polyethylenes have melt flow rates, respectively, of about 26, 40, 25 and 12. Fiber forming polypropylenes include Exxon Chemical Company""s ESCORENE(copyright) PD 3445 polypropylene and Montell Chemical Co.""s PF304. Many other polyolefins are also available.
Natural fibers include wool, cotton, flax, hemp and wood pulp. Wood pulps include standard softwood fluffing grade such as NB-416 (Weyerhaeuser Corporation, Tacoma, Wash.) and CR-1654 (US Alliance Pulp Mills, Coosa, Ala.). Pulp may be modified in order to enhance the inherent characteristics of the fibers and their processability. Curl may be imparted to the fibers by methods including chemical treatment or mechanical twisting. Curl is typically imparted before crosslinking or stiffening. Pulps may be stiffened by the use of crosslinking agents such as formaldehyde or its derivatives, glutaraldehyde, epichlorohydrin, methylolated compounds such as urea or urea derivatives, dialdehydes such as maleic anhydride, non-methylolated urea derivatives, citric acid or other polycarboxylic acids. Some of these agents are less preferable than others due to environmental and health concerns. Pulp may also be stiffened by the use of heat or caustic treatments such as mercerization. Examples of these types of fibers include NHB416 which is a chemically crosslinked southern softwood pulp fibers which enhances wet modulus, available from the Weyerhaeuser Corporation of Tacoma, Wash. Other useful pulps are debonded pulp (NF405) also from Weyerhaeuser. HPZ3 from Buckeye Technologies, Inc of Memphis, Tenn., has a chemical treatment that sets in a curl and twist, in addition to imparting added dry and wet stiffness and resilience to the fiber. Another suitable pulp is Buckeye HPF2 pulp and still another is IP SUPERSOFT(copyright) from International Paper Corporation. Suitable rayon fibers are 1.5 denier Merge 18453 fibers from Tencel Incorporated of Axis, Ala.
Examples and Comparative Examples, follow:

Nonwoven composite with high pre-and post-wetting permeability


The present invention is generally directed towards the field of lancing aids in which disposable lancet systems are used. The lancet system according to the invention has a needle body which surrounds the needle tip in a lancet system in a protective manner and also comprises a protection against re-use of an ejected lancet system.

In a variety of diseases it is necessary to examine human blood for an analyte contained therein. In many cases this only requires the withdrawal of a small amount of blood in the form of a blood drop by producing a small puncture wound. A particularly important example of such a case is diabetes in which the glucose content of blood has to be examined at regular intervals. Blood may also for example be examined with regard to coagulation parameters, triglycerides, HbA1c or lactate. Blood lancet devices which consist of a lancing aid and a tailor-made replaceable lancet are usually used to produce the required puncture wounds. The housing of the lancet instrument contains a lancet holder in which one interchangeable lancet can be inserted. During the lancing operation the lancet holder is rapidly moved in a lancing direction by a lancet drive of the lancet which is also integrated into the lancing aid until the needle tip emerges from an exit opening provided at the front end of the lancing aid and produces a small puncture wound in the part of the body that is pressed against the front end. Afterwards the lancet holder containing the lancet is moved back in the opposite direction to lancing.
Small, easy-to-handle blood collection devices, so-called lancing aids that can be easily and reliably operated by the user and enable a part of the body to be lanced in an almost painless manner are now routinely used. In order to avoid infections especially in hospitals, the lancets are disposable elements intended for single use. After a lancet has been used once, the lancet is removed after the lancing operation or ejected from the device and discarded as refuse. In such a case the exposed needles in a refuse container may lead to injury during waste disposal resulting in a contamination of other persons by the used lancet. Such contamination may lead to infections and thus some countries are planning to impose a ban on blood collection systems in which the needle tip is freely accessible after use. In addition to a risk of injury during waste disposal there is also a risk that a used lancet may be accidentally re-used. This is particularly relevant for hospitals in which a lancing aid is used for several patients since such inadvertence of the nursing staff could lead to a patient being contaminated with the blood of a previous patient.
In addition to the use of blood lancet devices by medical staff, lancing aids are also used by laymen in the so-called home-monitoring field. This is particularly the case for monitoring the treatment of diabetics. Thus it has been found in the treatment of diabetics that serious damage associated with diabetes such as loss of sight can be substantially reduced when the glucose concentration in the blood of the diabetic is determined frequently and up to five times daily and the insulin injection is exactly adjusted on the basis of these measurements. Lancing aids which enable the diabetic to carry out such a blood examination are used for home-monitoring in order to carry out such frequent measurements. The resulting requirements for a blood lancet device are a simple handling when inserting new lancets and a reliable ejection of used lancets in addition to a simple handling when triggering the lancing operation and a relatively painless puncture. Lancet replacement should on the one hand be as simple as possible and, on the other hand, ensure the utmost safety with regard to unintentional injury of the user or other persons. Although in the home-monitoring field it is conceivable that a lancet, once inserted, is used several times for lancing by the same user, even in this case an accidental re-use of an ejected lancet should be prevented once the user has decided to discard the lancet. Furthermore other persons in particular should be reliably protected from the discarded lancets for example during waste disposal.
In the prior art the tip of the needle is usually surrounded by a tip cover made of plastic when the lancet is inserted which allows a safe insertion of the lancet. When the lancet is inserted, the tip cover is removed to expose the sharp tip of the needle for the lancing operation (U.S. Pat. No. 5,628,765). However, due to the exposed needle tip there is a risk of accidental injury and the tip may become damaged. The lancet is removed from the lancing aid after one or several lancing operations. This can either be carried out manually in which case there is a high risk of injury by the needle tip or by an automatic ejection mechanism.
A blood lancet device is disclosed in the patent EP 0 565 970 in which the lancet is ejected from the lancet holder by means of an ejecting rod. The user can operate the ejecting rod by pressing a corresponding button.
Furthermore an ejecting mechanism is described in the patent document U.S. Pat. No. 4,442,836 where the needle is automatically released when the lancing aid is retensioned so that the used lancet is discarded after each lancing operation. Such ejecting mechanisms require a relatively high degree of additional engineering. Moreover multiple use of an already inserted lancet system is not possible which is, however, often desired by customers especially in the home-monitoring field. Another major disadvantage of the described prior art is that the needle tip is unprotected after the lancet has been ejected resulting in a risk of injury as described above.
In order to facilitate the safe removal of a used lancet, blood collection systems are also described in the prior art which ensure the needle tip is protected after ejecting the lancet. This is regarded as an important feature especially for elderly users or those that are handicapped by poor sight and shaking hands as a result of disease.
A protection of the needle tip is achieved in the prior art by integrating the lancet in a cap of the lancing aid such that the lancet and the housing cap together form a replaceable disposable unit. Such designs are described in the documents EP 0595148 and U.S. Pat. No. 4,990,154, U.S. Pat. No. 5,454,828 and DE 10053974. When the lancet is ejected by the user, the housing cap is placed over the needle tip so that the lancet surrounded by the cap can be subsequently discarded. Even if the needle tip is protected after ejection by the described mechanism, it is nevertheless possible for a careless user to reinsert a needle that has already been ejected once and carry out a new lancing operation. Consequently the user is instructed to recognize that the needle has already been used.
Only the document EP 0 630 609 discloses a mechanism which directly prevents reinsertion and thus re-use of a lancet that has been ejected once. The described lancet device comprises a needle with a needle body which breaks when the needle is ejected from the lancing aid to prevent a reinsertion of the needle. This prevents the user from re-using a contaminated needle. However, a disadvantage of the prior art is that the needle tip is unprotected after the needle has been ejected.
The object of the invention is to provide an easy-to-use lancing aid preferably for the home-monitoring field which prevents re-use of an already ejected lancet system and also ensures a protection from injury by the needle tip after the lancet system has been ejected. It should advantageously be possible to easily reuse a needle of a lancet system that has been inserted once.
The object is achieved by a lancing aid and a lancet system according to the independent claims. Preferred embodiments are derived from the dependent claims.
The invention concerns a lancet system and a lancing aid containing the lancet system. The lancing aid has a housing for inserting a lancet system. The housing also has an opening where the needle tip can emerge from the housing and a drive mechanism for carrying out a lancing operation.
According to the invention the housing additionally has a holding element which can interact with a corresponding holding element of the lancet system as soon as the lancet system has been inserted in the lancing aid. The interaction between the holding elements enables the lancet system to be positioned in the housing at a defined site. An exact positioning of the lancet system is important especially with regard to the drive mechanism for the lancing aid since it is the only way in which the needle can be correctly coupled to the drive mechanism such that the needle can perform a lancing operation at high speed and almost without vibration. This enables a rapid and relatively painless puncture in the intended part of the body. In addition to the described holding element, the lancet system for the lancing aid comprises at least one needle with a tip which is suitable for producing an opening in the skin. The needle is connected to a needle housing and at least one protective portion of the needle housing and the needle can be moved relative to one another. In a first position the needle tip is at least partially surrounded by the protective portion of the needle housing whereas in a second position the protective portion of the needle housing and the needle tip are disposed relative to one another such that the needle tip is released from the protective portion of the needle housing. If the protective portion of the needle housing is in its first position, it thus guards against injury by the lancet tip which is particularly important after the lancet system has been ejected from the lancing aid.
The needle housing also contains a blocking mechanism which is activated by an interaction with the lancing aid. The blocking mechanism changes the needle housing in such a manner that after the lancet system has been ejected from the lancing aid, the holding element on the lancing aid can no longer interact with the holding element of the lancet system when it is reinserted. This prevents re-use of a lancet system that has been ejected once. In this connection the blocking mechanism can be automatically actuated as soon as certain operating steps have been carried out on the lancing aid. However, other embodiments are conceivable in which the user actuates the blocking mechanism by a separate operating step.
As a result of the special design of the needle housing, the lancet system according to the invention provides a protection from the needle tip such that after ejection from the lancet system the tip is surrounded by the protective portion of the needle housing to such an extent that injury by the tip is prevented. The blocking mechanism also influences the interaction of the holding elements. Within the scope of the invention the term interaction of the holding elements encompasses any conceivable embodiment that is known in the prior art for inserting and positioning a lancet or a magazine in a lancing aid. For example the holding elements can be snapped in or clamped. Suitable holding elements for this may for example be designed as locking lugs, grooves or hooks to name only a few possible embodiments. Similarly to the systems described in the prior art containing individual lancets, it is also conceivable that the lancet system is already adequately positioned and held in the lancing aid due to its coupling to the drive unit so that for example the drive unit itself can be used as a holding element for an appropriately designed lancet system.
If several holding elements are provided to position the lancet system, the blocking mechanism advantageously prevents an interaction between the holding elements of the lancet system and the lancing aid so that the lancet system cannot be held and positioned in the lancing aid. This is particularly advantageous when the lancet system and lancing aid each have several holding elements that act independently of one another.
In a preferred embodiment the interaction of the holding elements is blocked in such a manner that the lancet system is prevented from being reinserted in the lancing aid. Within the scope of the invention the term "reinsertion" encompasses a handling of the lancet system such that the lancet system is positioned at the position in the lancing aid intended for carrying out the lancing operation and is held there due to the interaction of the holding elements. For this purpose the lancet system is again used at its original position in the lancing aid thus restoring the original state of the lancet system and lancing aid which was present when the lancing aid was first used.
When operating the lancing aid, the user can advantageously immediately and unambiguously identify an already used lancet system for example due to the fact that a reinsertion of the lancet magazine into the lancing aid is blocked. Hence in contrast to the prior art the user is not required to consciously distinguish between a used lancet system and a new lancet system. Advantageously the user is spared an unnecessary reinsertion of a used lancet system which no longer functions which elderly and visually handicapped persons often find to be difficult.
However, it is also possible that the blocking mechanism only blocks the lancing operation in which case it is possible to reinsert a needle that has already been ejected. If a reinsertion of the lancet system is prevented, this usually means that the lancet system cannot couple to the drive unit.
In a preferred embodiment the blocking mechanism is essentially achieved by a change in the shape of the needle housing. This proves to be particularly advantageous when the shape of the needle housing itself forms at least a part of a holding element. It is also possible that a deformation of the needle housing spatially separates the holding elements in the lancing aid such that the blocking mechanism has an indirect effect on a holding element without directly acting on it. Hence the lancet system can no longer be positioned and held at a defined position in the lancing aid. In a preferred embodiment the deformation of the needle housing transfers the protective portion of the needle housing to a first position such that there is no risk of injury when disposing a used lancet. The protective portion of the needle housing and the blocking mechanism are then achieved as a single component of the lancet system.
In principle the holding elements can interact in a variety of ways. The blocking mechanism may have a direct or indirect effect on the holding elements. In the case of a direct effect on the holding elements, at least one holding element is advantageously changed, covered or destroyed in such a manner that interaction of the holding elements is no longer possible. Furthermore embodiments are also conceivable in which the lancet system is positioned within a lancing aid due to magnetic properties of the system. Hence a change in the magnetic properties of the needle housing could prevent a re-use of the lancet system. Appropriate magnetic elements of the needle housing or lancing aid are then the holding elements of the system.
Since the blocking mechanism advantageously only prevents a repeated insertion of the lancet system but does not prevent re-use of a needle that has already been inserted, the lancet system also satisfies requirements in the home-monitoring field where multiple use of a once inserted needle is often desired.
The lancing aid according to the invention for collecting blood has a drive unit with a plunger which moves a needle from its resting position into a lancing position. A number of drive mechanisms are known in the prior art that can be used in the field of blood collection devices (e.g. U.S. Pat. No. 5,314,442, WO 00102482, U.S. Pat. No. 3,030,959). In particular drive mechanisms are frequently used which draw their energy from a previously tensioned spring. Drive units are preferably used within the scope of the present invention which enable a guided movement of the plunger and needle for example as a result of a form-fitting coupling as described in the document DE 10053974. Guided movements of the needle for example by means of guide blocks have also been previously described in EP 0 565 970. Such drive mechanisms are preferred because the puncture is less painful. However, the system according to the invention is not limited to a particular drive mechanism, but on the contrary, can be combined with a variety of drive units.
An important aspect of the invention is a lancet system that can be detached from the drive unit containing at least one needle where the lancet system is provided as a disposable unit. In this connection the term needle encompasses a blade-shaped substantially flat lancing unit and all other conceivable embodiments thereof. In principle needles can be used for the invention that are basically well known in the prior art and can be used in a lancet system. In the prior art a needle is often combined with a base body that can couple to the lancing aid which is referred to as a lancet. Such lancets often have a base body made of plastic in which a metal needle is disposed. According to the invention it is possible to integrate such a lancet into the lancet system according to the invention. It is for example conceivable that the needle housing according to the invention contains a base body like that used for lancets in the prior art, where the inventive functionality of the system is maintained by integration of the base body. In this case the lancet system has an at least two-part design according to the described embodiment. In a preferred embodiment the needle housing is designed such that a plurality of lancets is disposed in the needle housing such that the needle housing represents a magazine containing a plurality of lancets and each base body of the lancet represents a needle body. Consequently in a preferred embodiment the protective portion of the needle housing is formed by the magazine housing. The needle and the base body can then be guided in a movable manner within the magazine. The needles within a needle housing designed according to the invention as a magazine are preferably present in separate chambers in order to prevent contamination of unused needles by used needles when reloading.
In order to carry out a lancing operation, portions of the needle body are advantageously designed like the system already described in DE 10053974 such that the individual needles of the system can be actively coupled to the drive unit of the lancing aid. Embodiments that can also be used to drive needles within a magazine of a lancing aid are described for example in the documents DE 10053974, U.S. Pat. No. 4,990,154 and U.S. Pat. No. 5,074,872. The chambers arranged next to one another in which the lancets are individually located are positioned successively relative to the drive unit in order to carry out a lancing operation in such a manner that in each case a single needle can be coupled to the plunger of the drive unit. Also in this case magazines in the form of a drum containing chambers in which the needles are located parallel to the longitudinal axis of the drum have also proven to be particularly advantageous.
The lancet system also advantageously comprises a needle housing which at least partially surrounds the needle tip by the protective portion of the housing when the needle is in its resting position. In order to carry out the lancing operation, the protective portion of the needle housing is spatially separated from the needle tip so that the protective portion of the needle housing does not hinder the lancing operation. When the lancet system is ejected from the lancing aid the needle remains in its resting position so that the ejected needle tip is protected and additionally the blocking mechanism according to the invention prevents a re-use of the lancet system. It is, however, also possible that the protective portion of the needle housing is not transferred to its first position until the lancet system is ejected so that the needle tip is only protected as a result of the ejection. In a preferred embodiment an unused needle is also in a resting position before insertion into the lancing aid to prevent injury by the needle tip and contamination when the needle is inserted as well as after ejection.
A blocking mechanism according to the invention can be actuated for example when the lancet system is ejected from or inserted into the lancing aid independently of the needle tip protection. In principle the blocking mechanism or the needle tip guards can also be activated separately or by means of individual operating steps of the lancing aid e.g. during the lancing operation. In general all possible combinations are conceivable which ensure a simultaneous or successive blocking mechanism and protection of the needle tip.
The blocking mechanism can have a variety of designs but it is advantageous that the shape of the needle housing is changed in such a manner that it is no longer possible to reinsert a lancet system once it has been ejected. For example the blocking mechanism can move at least one part of the needle housing that interacts with the lancing aid in such a manner that a change in its position blocks a reinsertion of the lancet system. This is for example the case when the blocking mechanism closes a recess in the needle housing which forms a holding element or a recess is generated in the needle housing that is essential for an interaction of the lancet system with a lancing aid. Furthermore it is also possible that the blocking mechanism comprises a predetermined breaking point which results in a breaking of the needle housing when the lancet system is ejected. It is also conceivable that the needle housing is enlarged, made smaller or bent which are only a few methods for deforming the needle housing.
According to the invention an interaction between the lancet system and lancing aid activates the blocking mechanism and sets a first position of the protective portion where the protective portion at least partially surrounds the needle tip.
An important requirement for the lancet system is that the needle tip that is used to produce a wound in an appropriate part of the body is sterile. The sterility of the needle tip has to be ensured over a long period which extends from the manufacture of the lancet system up to its use. Sterility can be achieved during the manufacture of the lancet system by for example gamma radiation which is commonly used in the prior art. In order to maintain sterility, the lancet system can be sealed in a wrapping, for example a polyethylene bag. In another embodiment the opening of the lancet system where the needle tip emerges from the protective portion of the needle housing can for example be closed by a sealing foil. These are preferably detachable sealing foils which the user removes before using the lancet system. However, it is also possible to use thin foils which are not pierced by the needle tip until the needle is used so that the user does not have to carry out additional handling steps. Such foils may already be used as an integral part of the manufacturing process for the lancet system which is usually by means of an injection moulding process.
Furthermore in the prior art an elastomer is described in the application WO 01/66010 for sterile protection which encloses the needle tip and thus protects it against contamination. This sterile protection can either be pierced during the lancing operation or be removed by the operator before use.
In another advantageous embodiment the protective portion of the needle housing can comprise a sterile protection and/or the protective portion can be essentially formed thereby. In this case the elastomer of the sterile protection serves for example as the protective portion of the needle housing by the fact that the needle tip can be moved in a guided manner relative to the elastomer. Another part of the needle housing that can be actuated independently of the sterile protection is able to change the needle housing and represents the blocking mechanism. This requires that the sterile protection can reversibly expose the needle tip and surround it again which is for example the case with an elastomer protection (WO 01/66010) in which the elastomer is firstly pierced during the lancing operation and subsequently the needle tip is retracted into the elastomer. Consequently in this example the needle tip changes its position relative to the sterile protection during the lancing operation and the needle tip is protected by the sterile protection in its resting position after the lancing operation. In principle many embodiments of a sterile protection are conceivable and hence the inventive system is not limited to any special embodiment of a sterile protection.
Further features and advantages of the invention will become apparent from the following discussion and the accompanying drawings in which: The system according to the invention is illustrated in the following on the basis of the figures and examples without being thereby limited to the individual examples.

Lancing aid comprising a lancet system that is protected against re-use